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The iPhone has had a 3.5 inch screen since its release. That probably isn't going to change.

Every app in the App Store is made with the loving fact that it will work on all iPod Touches and iPhones alike. Why is this? Because the screen sizes are all the same. Some apps have adapted for the retina display, some are still running on the resolution of the iPhone 3GS and older. They all have one thing in common; a 3.5 inch display.

So what is it that makes the iPhone's 3.5 inch screen a hit? That's an interesting question to think about. Especially since there are other phones selling high amounts with absolutely massive screens. The Galaxy S II, pictured above, has a screen that is almost an inch larger than the iPhone 4S's screen.

A designer, named Dustin Curtis has a very good speculation to put into perspective for all of us:

Originally Posted by Dustin Curtis:I’ve been wondering why Apple chose to make the iPhone 4′s screen 3.5-inches when other comparable phones with Android and Windows Phone 7 have larger, more inviting screens. When you first see a phone with a 4-inch or larger screen, it seems like a much better experience. I thought it was a technical decision, and it could be, but since switching to an Android phone — a Samsung Galaxy S II, the “best Android phone you can buy, anywhere” — 15 days ago, I have realized another huge downside of larger screens: when holding the phone with one hand, I can’t reach the other side of the screen with my thumb.

Touching the upper right corner of the screen on the Galaxy S II using one hand, with its 4.27-inch screen, while you’re walking down the street looking at Google Maps, is extremely difficult and frustrating. I pulled out my iPhone 4 to do a quick test, and it turns out that when you hold the iPhone in your left hand and articulate your thumb, you can reach almost exactly to the other side of the screen. This means it’s easy to touch any area of the screen while holding the phone in one hand, with your thumb. It is almost impossible to do this on the Galaxy S II.

The idea that Curtis is putting onto the table is that the specifically fixed 3.5 inch screen makes one-handed use much easier. It's not impossible to use one hand with the 4.27 inch Galaxy S II, although you really need to wrench your hand across the phone to reach. This comes with the chance of dropping it, or having to use a second hand. When you're holding your phone with one hand, chances are that you're using the other hand for something else, although many times I find myself just lazily having one hand in my pocket while enjoying the fact that it's there.

As indicated by the image above, the average thumb-span of phone users meets the criteria of of the green area when the phone is held in portrait position. As shown, most of the iPhone's screen is very accessible by the thumb when the hand is placed in a comfortable position on the phone. When the same is done on the larger screen, an average sized thumb won't be able to reach without some major extension or wrenching of one's hand.

On the iPhone, there are usually navigation buttons on both the top left and top right of the screen. It's nice to be able to reach both in a tight situation, although on the larger screen the top right navigation button would be inaccessible.

When holding the phone in landscape mode, two hands usually support the phone. So on a larger screen, both thumbs cover most of the area accessible to input data into the phone. In this case, landscape orientation appears to be good for both handsets. The weakness of larger screens is portrait mode where people generally don't use two hands unless it's necessary. It generally feels pretty awkward to hold a small device with two hands. I would find myself using two hands on a larger screen more so than on the iPhone; it seems like that would get pretty inconvenient if I was multitasking and needed my other hand.

I find myself many times using two hands when my arms are propped over a desk. When I'm walking, standing, or laying down, I mostly only use one hand. I think I'm pretty content with this screen size and I'm not sure I'd like a larger screen. The 3.5 inch screen seems to be great for ergonomics.

Where does the 'bigger screen' come to an end? What will happen if a company comes out with a 5.5-6 inch smartphone screen? Why not just buy a 3G tablet? Perhaps the most important question to ask, is, what kind of device are you looking for?

I would have to continue to support the iPhone's current screen size. How do you cope with your 3.5 inch iPod Touch or iPhone screen? Do you own a larger screen? If so leave a comment below on how this perspective made you think about your screen size!

I think 4" would be the perfect size with a retina display. If Apple stayed with the 3.5" display I'd probably still stay with iPhone from what I've seen from phones with larger displays. The pros on the iPhone and iOS outweigh my main con which is the screen not being 4".

I think 4" would be the perfect size with a retina display. If Apple stayed with the 3.5" display I'd probably still stay with iPhone from what I've seen from phones with larger displays. The pros on the iPhone and iOS outweigh my main con which is the screen not being 4".

If they changed the screen size, EVERY app in the App Store would have to be re-written.

I personally like the 3.5" screen, any bigger and you might as well hold a brick in your hand. If they can make the screen bigger in the same form factor then I am fine with that but you can't make too much bigger screen within the current iphone case size. All in all, 3.5" is perfect imo.

Very well written article. I had never thought of it like that but I can comfortably hold the iPhone in one hand and type a quick text or email. I always liked the iPhone's screen, and if they went to a larger screen I honestly don't know if I would buy one. Plus the iPhone's screen is higher resolution than most of the 4" and larger screens out there.

Originally Posted by iLoveWindows&iPhone

No.... This logic would work if you have had your otter hand bitten off by a shark...

I use two hands the majority of the time I'm using my iPhone. Texting...two hands. Browsing...2 hands. I could think of more examples, but you get my point.

I own a iP4 and a Galaxy S2 and I don't have one-hand issues with either phone.

then again, i can palm a basketball

lol seriously, i think the overall size thing also plays a big part in what i call "pocket convenience." My iPhone travels in and out of my pocket much faster than the S2. It's real easy to mess with while on the go, whereas with my S2 i tend to pay more attention to the phone, stop walking/moving etc even if just to check an email or send a quick text.

or maybe that's because I've had all iphones since the first one and i'm super comfortable with 'em.

I think Apple has the perfect blend of performance, specs and usability.

And you (writer) said that apps work on all idevices because of this screen size? I think that should be questioned as Samsung Galaxy SII is 800x400 pxls and still looks very sharp. So they could up iphone screen to 4 inch but keep the 960x720 resolution then it would work with existing apps right?

A friend of mind the other day got a new android device and I was like dude why you talking on a tablet. It was freakin huge. I mean for real iPhone is practical. Fits nice in pocket, easy to handle and just right to watch an occasional video.

I don't know where you've been, but this topic is probably the #1 thing that had people on the fence with the 4S. It's been a big issue for a long time, and while the points in this article have all been brought up to some degree at times, this is the most informative and comprehensive account on this site that I can think of.

Please, don't be disrespectful to the writers who provide this content in the hopes of actually helping people.

How so? The iPad runs iPhone apps no problem in full size. There is some visual quality loss on an iPad, but if it was scaling up a 1/2 inch to 4" it would be fine.

I'm sure if you've ran an iPhone 3GS quality app on the iPhone 4's retina display, you'd have seen an unsightly distortion due to resolution issues. If the screen were scaled upwards, quality loss would show the same events as upgrading from an iPhone 3GS to an iPhone 4. Keeping a screen of the same aspect ratio is very important and makes developing apps easier for the developers - and a more global experience for the users. At the same time, while the iPad can run iPhone-sized applications in full screen, I have found this to be a not-so-eyecandy experience and I would never like to run my applications in that manner. Any kind of upwards scaling will cause issues on a resolution set to a specific size and aspect ratio.

You guys realize that you can make the screen bigger without making the phone bigger right?

Not as easy as it sounds, and if your response is going to be, "just make the screen edge to edge" then you should try that and see if the rest of the hardware will fit. Good luck.

Originally Posted by NegativeBeef

Really? Then how come android apps don't have to be rewritten for difference sized screens then? You've obviously never heard of upscaling.

Uh, because android apps are written with a number of resolutions prebuilt into them. If you haven't noticed all android phones have the same aspect ratio IF the screen sizes are tantamount to that ratio.